It is well known in the construction industry that significant economic savings can be realized by reducing the amount of work required at the construction site. To achieve this objective, prefabrication has been adopted on a large scale in the construction industry, both with respect to general purpose buildings and with respect to personal housing. For example, some sources have estimated that as many as forty percent (40%) of the homes now being built use some form of premanufactured structural components. Moreover, four and seven-tenths percent (4.7%) of all housing starts in the United States in 1991 are homes that are completely modular, and this percentage is expected to rise. The ultimate goal to be achieved in building modular structures has been to produce, at a remote site and in a factory environment, as many of the components of a given structure as possible, leaving only site preparation and final assembly to be done at the actual location where the building is to be situated.
There are a number of advantages to be achieved by prefabrication. The most obvious of those advantages is the significant reduction of time and labor required at the job site, where labor costs are normally the highest. In addition to the reduced time required for actual erection of the building, other time savings are also possible. For example, the reduced amount of work time at the job site diminishes the potential for interruptions resulting from inclement weather. Reduced time at a job site can also drastically reduce the potential for work-related injuries and/or deaths. A controlled factory atmosphere is inherently amenable to measures for reducing injuries and increasing safety.
Furthermore, increased uniformity of the structural components resulting from the enhanced quality control possible in a factory atmosphere and the economic advantages of mass production techniques are also achievable with the prefabrication approach. As is often the situation, the use of standardized, prefabricated structural components not only improves the uniformity of the end product but also greatly simplifies the actual erection process. This last feature also makes it possible to produce quality buildings with unskilled, or minimally skilled, personnel. Thus, the overall results of prefabrication in the construction industry include greatly improved efficiency, significantly reduced costs, lower accident rates and better safety records.
These advantages are, of course, desirable in any type of construction, but are believed to be especially important in the production of individual dwellings, particularly in economically distressed areas and in third world countries where cost is one of the most significant obstacles to overcome.
There are a wide variety of practical ways of to effectuate the prefabrication concept.
For example, the Crowe U.S. Pat. No. 1,998,448 discloses the factory prefabrication of steel frame panel units of standard dimensions which are filled with cementitious material and assembled so as to leave vertical spaces between adjacent vertical walls for utility connection and with laterally adjacent panels being joined by cover strips or slabs which are interconnected thereto.
The Wagner U.S. Pat. No. 2,850,771 discloses a prefabricated construction system wherein wooden panels are interconnected to vertical posts or columns with the vertical edges of the wooden wall panels and the posts having grooved areas and with spline blocks being used to interconnect the two.
The Paul U.S. Pat. No. 3,229,431 is indicative of another approach wherein a so-called "frameless" modular multi-story building is constructed from self-contained prefabricated modules which are simply set on a building foundation and attached thereto by anchor bolts secured in the foundation.
The Bolt U.S. Pat. No. 3,284,966 is of general interest in showing a prefabricated building which can be readily assembled, or erected, at the job site and which is collapsible for transportation purposes.
The Moore U.S. Pat. No. 3,783,563 discloses a prefabricated building constructed of panels formed of molded plastic material, reinforced with glass fibers, and wherein the panels have channels or ribs on their edges adapted to mate with complementary structures of connector members.
Other examples of prefabricated construction components utilizing various plastic materials can be seen in the Kennedy U.S. Pat. No. 2,918,151; the Espeland U.S. Pat. No. 3,662,507; the Sohns U.S. Pat. No. 3,397,496; and, the Farge U.S. Pat. No. 4,183,185.
The foregoing patents are believed to be generally representative of the prior art, and that art does illustrate some diverse approaches to the prefabrication of buildings using various materials. However, none of the aforesaid prior art patents, nor any other prior art with which the inventor is aware, either alone or in combination, achieve the several objects of the present invention.
Other more advanced structures are disclosed in U.S. patent applications Ser. No. 07/792,356, filed Nov. 14, 1991; Ser. No. 07/875,097, filed Apr. 28, 1992 and Ser. No. 07/893,532, filed Jun. 4, 1992, the subject of each the aforesaid applications are the inventions of the present inventor and are incorporated herein by reference. The aforesaid applications describe various aspects of modular building structures with which the present invention can be advantageously employed.